Asteroid (101955) Bennu, a near‐Earth object with a primitive carbonaceous chondrite‐like composition, was observed by the Origins, Spectral Interpretation, Resource Identification, and Security‐Regolith Explorer (OSIRIS‐REx) spacecraft to undergo multiple particle ejection events near perihelion between December 2018 and February 2019. The three largest events observed during this period, which all occurred 3.5 to 6 hr after local noon, placed numerous particles <10 cm on temporary orbits around Bennu. Here we examine whether these events could have been produced by sporadic meteoroid impacts using the National Aeronautics and Space Administration's (NASA) Meteoroid Engineering Model 3.0. Most projectiles that impact Bennu come from nearly isotropic or Jupiter‐family comets and have evolved toward the Sun by Poynting‐Robertson drag. We find that 7,000‐J impacts on Bennu occur with a biweekly cadence near perihelion, with a preference to strike in the late afternoon (~6 pm local time). This timing matches observations. Crater scaling laws also indicate that these impact energies can reproduce the sizes and masses of the largest observed particles, provided the surface has the cohesive properties of weak, porous materials. Bennu's ejection events could be caused by the same kinds of meteoroid impacts that created the Moon's asymmetric debris cloud observed by the Lunar Atmosphere and Dust Environment Explorer (LADEE). Our findings also suggest that fewer ejection events should take place as Bennu moves further away from the Sun, a result that can be tested with future observations.

中文翻译：

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流星体撞击是贝努粒子喷射事件的来源


小行星 (101955) Bennu 是一个具有原始碳质球粒陨石状成分的近地天体，由起源、光谱解释、资源识别和安全风化层探测器 (OSIRIS-REx) 航天器观测到，它在附近经历了多次粒子喷射事件。 2018 年 12 月至 2019 年 2 月期间观测到的近日点。在此期间观察到的三个最大事件均发生在当地正午后 3.5 至 6 小时，将大量 <10 厘米的粒子放置在贝努周围的临时轨道上。在这里，我们使用美国国家航空航天局 (NASA) 流星体工程模型 3.0 检查这些事件是否可能是由零星流星体撞击产生的。大多数撞击本努的射弹来自近各向同性彗星或木星族彗星，并通过坡印廷-罗伯逊阻力向太阳演化。我们发现，7,000-J 对贝努的撞击在近日点附近以每两周一次的频率发生，并且倾向于在下午晚些时候（当地时间下午 6 点左右）撞击。这个时间与观察结果相符。陨石坑缩放定律还表明，只要表面具有弱多孔材料的内聚特性，这些冲击能量就可以重现观察到的最大颗粒的尺寸和质量。本努的喷射事件可能是由月球大气和尘埃环境探测器（LADEE）观测到的流星体撞击造成的，这种撞击产生了月球不对称的碎片云。我们的研究结果还表明，随着贝努远离太阳，发生的喷射事件应该会减少，这一结果可以通过未来的观测进行检验。